Gas turbines usually comprise a compressor section, a combustor and at least one turbine. Within the compressor section alternating rows of running blades and guiding vanes interact with the combustion air as it is compressed in an annular gas channel to be used in the combustor for burning a fuel. While the running blades are mounted on a central rotor, the guiding vanes are stationary and mounted on suitable compressor vane carriers (CVCs), which concentrically surround and border the gas channel.
It is well-known in the prior art to use CVCs completely made of low thermal expansion material, e.g. a Ni-base alloy. When applied to an industrial (stationary) gas turbine (GT) of, for example, 50 MW power, this design is advantageous, because it brings a high clearance reduction and thus improves the overall efficiency of the machine. However, it is extremely expensive for a large GT to have a CVC, which is completely made of low thermal expansion material.
It has therefore already been proposed to use a hybrid design of the CVC, where the cylindrical part is made of several segments made of standard, low alloyed steel and the supporting structure, which is defining the clearances, made of low thermal expansion material (see document US 2012/0045312 A1). This solution has its disadvantages, because the segmented, cylindrical part is assumed to be prone to significant thermal distortions. This is because the segments are relatively long and do not support each other. Also, the longitudinal gaps between the segments could be a source of excitation for the compressor blading.
Document WO 2010023150 A1 relates to a guide vane support for an axial-flow, stationary gas turbine, comprising a tubular wall with an inflow-side end and an outflow-side end opposite the inflow-side end for fluid flowing within the guide vane support in a flow path of the gas turbine, wherein at least one cooling channel for a coolant is provided in the wall. In order to provide a guide vane support that is suitable for especially high operating temperatures and that can nevertheless be manufactured comparatively inexpensively, it is proposed that the turbine vane support be designed in multi-layered fashion—as seen in the radial direction. The different layers of the guide vane support can be connected together using hot isostatic pressing, wherein the inner layers of the guide vane support can be manufactured from a high-temperature resistant material, whereas the exterior layers of the guide vane support can be manufactured from a less temperature resistant material. Also, by designing the guide vane support in multi-layered fashion, it is very easy to manufacture cooling channels inside the wall of the guide vane support. Although the use of expensive high temperature material is reduced, the manufacturing of the multi-layer elements is still expensive and time-consuming.